钎焊单层金刚石砂轮的现存问题及其对策

概述了用活性钎料将金刚石磨料钎焊到钢基体表面制作单层金刚石砂轮 ,比传统的单层电镀金刚石砂轮具有明显的工艺优势。分析指出了钎焊工艺的现存问题 ,即如何实现金刚石磨料与合金钎料层高的结合强度、钎料层厚度的均匀性和金刚石磨料的有序排布。给出了可行的解决方案 ,即利用Ag -Cu -Cr或Ni-Cr等活性钎料与金刚石界面化学反应生成的Cr7C3 和Cr2 3 C7实现钎料层与金刚石间的高强度结合 ;通过砂轮地貌优化 ,优化出磨粒排布方式 ,然后按优化的结果排布磨料。研制出了具有磨料出露高度高、有序排布、钎料层厚度一致性、高结合强度、高锋利度的单层钎焊金刚石砂轮。     

银基钎料钎焊单层金刚石砂轮的研究

概述了单层高温钎焊超硬磨料砂轮的优点。这种新型超硬磨料砂轮以其卓越的磨削性能在今后将逐步替代传统电镀砂轮。鉴于它极其广阔的应用前景,国内也必将大力开发此种单层钎焊超硬磨料砂轮。本文利用高频感应钎焊的方法,用Ag-Cu合金和Cr粉共同作中间层材料,在一定的钎焊温度和时间下,实现了金刚石与钢基体间的牢固结合。经扫描电镜分析发现Cr与金刚石之间形成CrC,与钢基体之间形成（FexCry)C,这是实现合金层与金刚石及钢基体之间都有较高结合强度的主要因素。最后通过磨削实验证实了金刚石确实有较高的把持强度。     

Cr、Ti金属粉改善Ag-Cu-Zn合金对金刚石的钎焊性能研究

本文通过在Ag-Cu-Zn钎料合金与金刚石之间添加Cr、Ti金属粉,改善Ag-Cu-Zn合金对金刚石的钎焊性能,并在不同的保护条件下(真空、Ar气体、无机盐覆盖、C粉覆盖)钎焊金刚石磨粒;采用扫描电镜和光学显微镜对钎焊金刚石表面形貌以及金刚石一钎料合金-钢基体之间界面的微观结构进行了观察;结果表明添加Cr粉可以在空气中对金刚石实现良好的钎焊,添加Ti粉则需要在真空中或者覆盖C粉才能保证钎焊效果较好;在金刚石与钎料合金的界面处发现Cr和Ti元素的富集,这提高了Ag-Cu-Zn合金对金刚石的润湿性.     

Study on the use of CuSnTi brazing alloy for induction brazing of diamond grits surface-treated by direct current plasma chemical vapor deposition

Induction brazing of diamond grits surface-treated by direct current plasma chemical vapor deposition (DC-PCVD) on a steel substrate was carried out in an argon atmosphere. A CuSnTi brazing alloy (with an approximate melting temperature of 900 °C) was used for this purpose. The diamond edges were exposed out of the brazing alloy to retain their sharpness. Relatively fine titanium–carbon compounds were formed with uniform interspaces on the brazed diamond surface when immersed in the brazing alloy. The liquid brazing alloy filled the interspaces, leading to increased bonding strength between the brazing alloy and diamond grits. Boring tests on diamond core drills brazed with the treated diamond grits and untreated diamond grits showed that the percentages of whole grain fracture and of pullout from the matrix of the brazed treated-diamond grits became lower.     

激光钎焊金刚石磨粒界面微结构分析

采用Ni基合金钎料,在Ar气保护条件下,对金刚石磨粒进行了激光钎焊试验研究.采用扫描电镜(SEM)和能谱仪(EDS)及X射线衍射仪(XRD)对钎焊金刚石试样进行理化分析,探讨了钎料与金刚石界面处碳化物的形成机理.结果表明,激光钎焊过程中在金刚石表面附近形成的富Cr层与金刚石表面的C元素反应生成碳化物,在钢基体结合界面上Ni-Cr合金钎料和钢基体中的元素相互扩散形成化学冶金结合.     

钎焊金刚石铣磨刀具磨粒粒度尺寸与排布间距对CFRP磨削质量的影响

碳纤维增强复合材料（carbon fiber reinforced plastics,CFRP）由于其低层间结合力和各向异性导致其加工过程中易出现分层、毛刺、撕裂等加工缺陷和刀具耐用度低等问题。采用有序排布钎焊金刚石磨削刀具及"以磨代切"加工工艺能够有效减轻分层缺陷。为制备出适合CFRP磨边加工的钎焊金刚石刀具,本试验制备了不同磨粒排布间距与不同磨粒粒度尺寸的5种刀具,对比分析了刀具结构变化对CFRP磨边加工磨削力与加工表面质量的影响。试验结果表明:在一定范围内,在相同磨粒排布间距和加工参数下,随着磨粒粒度尺寸变大,磨削力变化很小,加工表面质量变差;在相同磨粒粒度尺寸与加工参数下,随着磨粒排布间距减小,磨削力先增大后减小,加工表面质量变好。      

钎焊金刚石耐磨涂层制备及其磨损性能

为提高农机刃具类零件的抗磨粒磨损性能,提出一种钎焊金刚石耐磨涂层制备方法,在Q235钢基体上制备了不同粒径及镀覆状态的金刚石耐磨涂层,并与65Mn钢的摩擦磨损和抗磨粒磨损性能进行对比。采用扫描电镜(SEM)对涂层表面、涂层与钢基体界面、涂层磨损后的表面微观形貌进行表征,并分析涂层的磨损规律及机理。结果表明:钎焊金刚石涂层与钢基体结合良好,金刚石在涂层中均匀分布,涂层厚度约370 μm。钎焊金刚石涂层的耐磨性优于65Mn钢的,且随着金刚石粒径减小钎焊金刚石涂层的摩擦系数降低,涂层的耐磨性增大;钎焊镀钨金刚石涂层的抗摩擦磨损和磨粒磨损性能均高于钎焊未镀覆金刚石涂层的。      

提高钎焊金刚石工具质量的研究进展

详细地介绍了当前国内外钎焊工具的研究进展,主要包括:钎料组分选用,激光钎焊,表面镀覆金刚石的采用,钎焊工艺条件的优化,磨粒均匀/有序排布的实现,钎焊内应力的消除等,最后提出了目前亟待解决的问题。文中对众多的钎料合金,按照钎焊结合的实现原理,分成了两大类,即碳化钛类和碳化铬类,比传统的以合金组分划分显得更为简单而清晰。在新工艺方面着重介绍了采用激光束作为热源进行钎焊,激光钎焊加热速度快,能有效降低金刚石石墨化进程,而且能避免整体加热时工件易变形的特点。     

Brazed Diamond Micropowder Bur Fabricated by Supersonic Frequency Induction Heating for Precision Machining

The common brazed diamond micropowder bur fabricated in a vacuum furnace produces an even brazing alloy surface. The small brazed diamond grits show low outcropping from the brazing alloy surface, and the chip space between them is small. The bur shows a low grinding efficiency and poor heat dissipation. In this study, a brazed diamond micropowder bur was fabricated by supersonic frequency induction heating. The method afforded a fluctuant surface on the brazing alloy. The brazed diamond grits with an outcropping height distributed uniformly on the fluctuant surface. The fluctuant surface showed a certain chip space. These characteristics of the tool increased the grinding efficiency and decreased the temperature of the grinding arc area. The roughness R _a of the ceramic tile surface trimmed by the tool cylinder was between 0.09 and 0.12 μm. In the first 90 min, the decrease in the weight of the ceramic tile ground by the tool cylinder was higher than that ground by the tool fabricated in a vacuum furnace. When the ceramic tile was cylindrically ground, the temperature of the grinding arc area measured using a thermocouple remained below 70 °C.     

Interfacial characteristics of titanium coated micro-powder diamond abrasive tools fabricated by electroforming-brazing composite process

In this study, abrasive tools were fabricated by an electroforming-brazing composite process. The abrasive tools were prepared using micro-powder diamond (MPD) grits with and without titanium (Ti) coatings. The interface characteristics of the MPD diamond grits and filler alloy were investigated. The results show that the diamond grits are uniformly dispersed on the surface of the steel substrate without visible agglomeration, and the NiCr filler alloy has good wetting toward diamond grits. Compared to the uncoated diamond grits, the abrasive grains with a Ti coating have an ideal grain distribution and brazed joints, and no aggregation of Si element observed at its edge. There is a more stable carbide TiC that formed on its surface in addition to the chromium carbide. Furthermore, the coated diamond grits are not graphitized and show a better residual stress state. In the abrasive tools with Ti-coated diamond, numerous intermetallic compounds (IMCs) are formed in the brazing layer, but the formation of theγ-Ni-based solid solution is relatively slight. The IMCs increase the microhardness of the filler alloy and help improve the wear resistance of the solder layer.     

Brazing diamond grits onto a steel substrate using copper alloys as the filler metals

Surface-set diamond tools were fabricated by an active metal brazing process, using bronze (Cu-8.9Sn) powder and 316L stainless steel powder mixed to various ratios as the braze filler metals. The diamond grits were brazed onto a steel substrate at 1050 °C for 30 min in a dry hydrogen atmosphere. After brazing practice, an intermediate layer rich in chromium formed between the braze filler metal and diamond. A braze filler metal composed of 70 wt % bronze powder and 30 wt % stainless steel powder was found to be optimum in that the diamond grits were strongly impregnated in the filler metal by both mechanical and chemical types of holding. The diamond tools thus fabricated performed better than conventional nickel-plated diamond tools. In service, the braze filler metal wore at almost the same rate as the diamond grits, and no pullout of diamond grits or peeling of the filler metal layer took place.     

钎焊金刚石线锯拉伸力学性能及断口分析

使用Cu-Sn-Ti预合金粉末作为过渡层材料,实现了金刚石颗粒与0Cr18Ni9不锈钢丝的钎焊连接,制作了直径约为0.8 mm的金刚石线锯。通过拉伸试验,获得了钢丝及线锯的拉伸力学性能数据,分析了钎焊前后钢丝横截面金相组织,利用扫描电子显微镜观察钢丝及线锯断口微观形貌,并分析了其拉伸断裂机理。结果表明:金刚石颗粒通过钎焊牢固连接于0Cr18Ni9不锈钢丝表面,形成耐磨工作层。线锯的抗拉强度可以保持700 MPa以上,屈服强度保持600 MPa以上,塑性大幅提高。钢丝基体奥氏体长大,组织均匀性大幅提高。经钎焊热处理的钢丝及其制备的线锯的拉伸断裂方式为韧性断裂,钎焊金刚石线锯工作层拉伸失效形式为钎料合金层断裂并从金属丝基体表面剥离。      

钎焊法制造单层金刚石取孔钻及其界面微观结构

使用钎焊法制造了单层金刚石取孔钻,并与电镀单层金刚石取孔钻的加工性能进行了比较.发现由于具有高的金刚石出刃和结合强度,钎焊取孔钻的锋利度和寿命都优于电镀取孔钻.通过光学显微镜、扫描电子显微镜(SEM)、能谱分析(EDX)和X射线衍射等对钢基体-钎料合金-金刚石的界面微观结构和成分进行了观察和分析,发现钎料合金中的Ni,Cr元素向钢基体中有一定的扩散;而在钎料合金和金刚石上分别存在反应层.钎料合金反应层主要是金刚石表面的C原子扩散进入液相后与Cr反应生成的Cr3C2和Cr7C3,而金刚石反应层是石墨化金刚石表面的位错通道与Cr反应形成Cr3C2并渗透到一定的深度形成的.     

微粉金刚石表面镀钛对钎焊磨具性能的影响

在微粉金刚石磨具的制备过程中,金刚石热损伤和磨粒与结合剂间界面特性是影响磨具性能的主要因素。利用电铸与钎焊相结合的工艺把表面镀钛和未镀钛两种微粉金刚石磨料制备成磨具,并将其用于氧化铝陶瓷的磨削试验。通过对钎焊后金刚石磨粒与钎料的界面分析,磨削力、磨粒脱落率以及工件表面粗糙度的比较,探讨磨粒表面镀钛对钎焊微粉金刚石磨具性能的影响。结果表明,镀钛微粉金刚石表面镀层在钎焊过程中对微粉金刚石起到包裹隔离的作用,可以降低微粉金刚石的热损伤和石墨化;在利用两种钎焊微粉金刚石磨具磨削氧化铝陶瓷时,镀钛微粉金刚石磨具的磨削力较小,磨料的脱落率也较少,且工件表面粗糙度值更低。综合比较,磨粒表面镀钛后,可以减弱微粉金刚石的热损伤,提高磨具的磨削性能。     

Cr元素对Ni基无硼钎料钎焊金刚石的组织及性能影响

针对B元素易使钎焊金刚石接头出现较多硬脆相的问题，制备一种新型Ni–Cr–Si–Cu–Sn无硼活性钎料，分析Cr元素对钎料组织和钎焊金刚石试样性能的影响规律。结果表明:Cr元素具有细化钎料晶粒和调控钎料中各元素分布的作用，可以提高钎料合金的显微硬度。当Cr元素质量分数过高时，会使钎料的熔点升高，钎料的润湿性能下降。综合来说，含有质量分数为15%的Cr的无硼钎料性能最佳，钎焊金刚石试样的磨削性能较优良，接头处出现多种形状的Cr₇C₃相，实现了钎料对金刚石的高强度连接。      

钎焊金刚石砂轮磨削硬质合金温度的试验研究

根据半人工热电偶测温原理制备了磨削测温试样,利用感应钎焊金刚石砂轮和电镀金刚石砂轮进行硬质合金YG6的磨削试验,研究了磨削深度、工件进给速度对工件表面磨削温度的影响。试验结果表明:在相同的磨削参数下感应钎焊金刚石砂轮的磨削温度要远低于电镀金刚石砂轮,且随着磨削深度和工件进给速度的增大磨削温度上升较为平缓,钎焊金刚石砂轮磨粒出露高度高、容屑空间大,磨粒呈有序排布是磨削温度较低的主要原因。     

Microstructural characterization of diamond/CBN grains steel braze joint interface using Cu–Sn–Ti active filler alloy

In order to develop the new generation superhard abrasive tools of diamond and cubic boron nitride (CBN), the brazing joint experiments of diamond/CBN crystals and AISI 1045 steel matrix using Cu–Sn–Ti active filler powder alloy were investigated in vacuum furnace. The brazing temperature was 930 °C and the dwelling time was 20 min. Interfacial characteristics of the brazing joint among the diamond/CBN grains, the active filler layer and the steel substrate were analyzed using scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction techniques. The results indicated that Ti element in the Cu–Sn–Ti alloys diffused preferentially to the surface of diamond/CBN grits to form a Ti-rich reaction layer in the brazed joints by microanalyses. Moreover, the TiC, TiN and TiB₂ phases in diamond/CBN interface and Cu–Ti phase in steel interface were confirmed by X-ray diffraction phase analysis. The wetting and bonding reactions on diamond/CBN by melting Cu–Sn–Ti alloy were realized through the interfacial reaction products like TiC, TiN and TiB₂ compounds during the brazing process. The adhesive strength experiments of the joint interfaces revealed that the grains were not pulled out from the bond interface. The reliable bonding strength of brazed diamond/CBN grains to the steel substrate can meet the application requirements of high efficiency machining in the industrial field.     

Ni-Cr合金真空单层钎焊金刚石砂轮

单层高温钎焊超硬磨料砂轮具有传统电镀砂轮无法比拟的优异磨削性能 ,国内应及早研制开发应用此种砂轮。本文利用真空炉中钎焊的方法 ,用Ni Cr合金钎料 ,适当控制钎焊温度、保温时间和冷却速度 ,实现了金刚石与钢基体间的高强度连接。扫描电镜X射线能谱 ,结合金相及试样逐层的X射线结构分析 ,剖析了Ni Cr合金与金刚石和钢基体钎焊界面的微区组织结构 ;揭示了Ni Cr合金对金刚石和钢基体表面的浸润和钎焊机理。即在钎焊过程中会在金刚石界面形成富Cr层并与金刚石表面的C元素反应生成Cr7C3,在钢基体结合界面上Ni Cr合金和钢基体中的元素相互扩散形成冶金结合 ,这是实现合金层与金刚石和钢基体都有高结合强度的主要因素。最后重负荷磨削试验表明金刚石为正常磨损 ,没有整颗金刚石脱落 ,说明金刚石确有高的把持强度     

钎焊金刚石砂轮修整实验研究

单层钎焊金刚石砂轮的圆度轮廓精度由于受磨料粒径和钎焊结合剂层高度不均匀等因素的影响而使其难以在工程陶瓷等硬脆材料精密磨削中应用.然而单层钎焊金刚石砂轮的修整是直接对金刚石磨粒进行微量的磨损,修整难度大、效率低,因此,探讨快捷且精密的整形方法就成了解决其应用问题的关键技术之一.在本文研究中,分别采用铁基金刚石烧结磨块、钎焊细粒度金刚石板和氧化铝磨块三种整形工具对钎焊金刚石砂轮进行了磨削法整形实验研究,实验结果表明利用氧化铝磨块进行磨削修整效率极低;钎焊金刚石板磨削修整虽然效率高,但是对砂轮表面金刚石磨粒造成大量破碎磨损;铁基金刚石烧结磨块在整形过程中可稳定地以磨平方式磨损砂轮表面金刚石磨粒,经精密整形后的砂轮圆度轮廓精度较高,用其磨削工程陶瓷时工件表面的犁沟和裂纹明显减少.     

高温钎焊过程中Ni-Cr合金对金刚石磨粒静压强度的影响

采用C类(Ni82Cr7Si4.5B3.1Fe3)和E类(BNi76Cr15P9)两种钎料对金刚石进行真空炉中钎焊。通过静压强度测试对各种状态下的金刚石钎焊性能进行评价,并借助SEM以及拉曼光谱仪对金刚石表面碳化物的形貌和金刚石的石墨化进行检测分析。结果表明:钎焊高温对金刚石强度的影响较合金钎料的化学侵蚀作用而言小很多;触媒元素Ni、Fe和强碳化物形成元素Cr等引起的化学侵蚀,是导致金刚石静压强度降低的两个主要原因;不同品质的金刚石经过高温钎焊后,静压强度值出现不同程度的降低。